Fasteners and fastener delivery devices for affixing sheet-like materials to bone or tissue

ABSTRACT

An improved method for attaching a sheet-like implant to tissue or bone with a fastener having a first and second arm, and a bridge extending therebetween. Each of the first and second arms include a trunk portion including a longitudinally displaced first and second projections extending in opposite directions within a plane defined by the trunk portions. The method includes forming first and second pilot holes in the tissue or bone using a trocar, receiving the first and second trunk portions within their respective pilot holes, and applying a pullout force on the bridge to create an in-plane torque on each trunk such that the resistance to pullout is increased.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.13/889,737, filed on May 8, 2013, which is a Continuation of U.S.application Ser. No. 13/717,493 filed on Dec. 17, 2012, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/577,626 filedon Dec. 19, 2011, the disclosures of each incorporated herein byreference.

The present disclosure is related to the following commonly assignedapplications, the disclosures of which are incorporated herein byreference: U.S. Provisional Application No. 61/577,6121 filed on Dec.19, 2011; U.S. Provisional Application No. 61/577,632 filed on Dec. 19,2011; and U.S. Provisional Application No. 61/577,635 filed on Dec. 19,2011.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD

The present invention relates generally to orthopedic medicine andsurgery. More particularly, the present invention relates to methods andapparatus for delivery and fixation of sheet-like materials, such as fortreating tendons or like tissue of articulating joints such as tendonsin the rotator cuff of the shoulder.

BACKGROUND

The glenohumeral joint of the shoulder is found where the head of thehumerus mates with a shallow depression in the scapula. This shallowdepression is known as the glenoid fossa. Six muscles extend between thehumerus and scapula and actuate the glenohumeral joint. These sixmuscles include the deltoid, the teres major, and the four rotator cuffmuscles. The rotator cuff muscles are a complex of muscles. The musclesof the rotator cuff include the supraspinatus, the infraspinatus, thesubscapularis, and the teres minor. The centering and stabilizing rolesplayed by the rotator cuff muscles are critical to the proper functionof the shoulder. The rotator cuff muscles provide a wide variety ofmoments to rotate the humerus and to oppose unwanted components of thedeltoid and pectoral muscle forces.

The muscles of the rotator cuff arise from the scapula. The distaltendons of the rotator cuff muscles splay out and interdigitate to forma common continuous insertion on the humerus. The supraspinatus musclearises from the supraspinatus fossa of the posterior scapula, passesbeneath the acromion and the acromioclavicular joint, and attaches tothe superior aspect of the greater tuberosity. The mechanics of therotator cuff muscles are complex. The rotator cuff muscles rotate thehumerus with respect to the scapula, compress the humeral head into theglenoid fossa providing a critical stabilizing mechanism to the shoulder(known as concavity compression), and provide muscular balance. Thesupraspinatus and deltoid muscles are equally responsible for producingtorque about the shoulder joint in the functional planes of motion.

The rotator cuff muscles are critical elements of this shoulder musclebalance equation. The human shoulder has no fixed axis. In a specifiedposition, activation of a muscle creates a unique set of rotationalmoments. For example, the anterior deltoid can exert moments in forwardelevation, internal rotation, and cross-body movement. If forwardelevation is to occur without rotation, the cross-body and internalrotation moments of this muscle must be neutralized by other muscles,such as the posterior deltoid and infraspinatus. The timing andmagnitude of these balancing muscle effects must be preciselycoordinated to avoid unwanted directions of humeral motion. Thus thesimplified view of muscles as isolated motors, or as members of forcecouples must give way to an understanding that all shoulder musclesfunction together in a precisely coordinated way—opposing musclescanceling out undesired elements leaving only the net torque necessaryto produce the desired action. Injury to any of these soft tissues cangreatly inhibit ranges and types of motion of the arm.

With its complexity, range of motion and extensive use, a common softtissue injury is damage to the rotator cuff or rotator cuff tendons.Damage to the rotator cuff is a potentially serious medical conditionthat may occur during hyperextension, from an acute traumatic tear orfrom overuse of the joint. With its critical role in abduction,rotational strength and torque production, the most common injuryassociated with the rotator cuff region is a strain or tear involvingthe supraspinatus tendon. A tear at the insertion site of the tendonwith the humerus, may result in the detachment of the tendon from thebone. This detachment may be partial or full, depending upon theseverity of the injury or damage. Additionally, the strain or tear canoccur within the tendon itself. Injuries to the supraspinatus tendon andcurrent modalities for treatment are defined by the type and degree oftear. The first type of tear is a full thickness tear, which as the termindicates is a tear that extends through the thickness of thesupraspinatus tendon regardless of whether it is completely tornlaterally. The second type of tear is a partial thickness tear which isfurther classified based on how much of the thickness is torn, whetherit is greater or less than about 50% of the thickness.

The accepted treatment for a full thickness tear or a partial thicknesstear greater than 50% includes reconnecting the torn tendon via sutures.For the partial thickness tears greater than 50%, the tear is completedto a full thickness tear by cutting the tendon prior to reconnection. Incontrast to the treatment of a full thickness tear or a partialthickness tear of greater than 50%, the current standard treatment for apartial thickness tear less than 50% usually involves physical cessationfrom use of the tendon, i.e., rest. Specific exercises can also beprescribed to strengthen and loosen the shoulder area. In manyinstances, the shoulder does not heal and the partial thickness tear canbe the source of chronic pain and stiffness. Further, the pain andstiffness may cause—restricted use of the limb which tends to result infurther degeneration or atrophy in the shoulder. Surgical interventionmay be required for a partial thickness tear of less than 50%, however,current treatment interventions do not include repair of the tendon, andrather the surgical procedure is directed to arthroscopic removal ofbone to relieve points of impingement or create a larger tunnel betweenthe tendon and bone that is believed to be causing tendon damage. Aspart of the treatment, degenerated tendon may also be removed using adebridement procedure in which tendon material is ablated. Again, thetendon partial thickness tear is not repaired. Several authors havereported satisfactory early post operative results from theseprocedures, but over time recurrent symptoms have been noted. In theevent of recurrent symptoms, many times a patient will “live with thepain”. This may result in less use of the arm and shoulder which causesfurther degeneration of the tendon and may lead to more extensivedamage. A tendon repair would then need to be done in a later procedureif the prescribed treatment for the partial tear was unsuccessful inrelieving pain and stiffness or over time the tear propagated throughinjury or degeneration to a full thickness tear or a partial thicknesstear greater than 50% with attendant pain and debilitation. A subsequentlater procedure would include the more drastic procedure of completingthe tear to full thickness and suturing the ends of the tendon backtogether. This procedure requires extensive rehabilitation, hasrelatively high failure rates and subjects the patient who firstpresented and was treated with a partial thickness tear less than 50% toa second surgical procedure.

As described above, adequate treatments do not currently exist forrepairing a partial thickness tear of less than 50% in the supraspinatustendon. Current procedures attempt to alleviate impingement or make roomfor movement of the tendon to prevent further damage and relievediscomfort but do not repair or strengthen the tendon. Use of the stilldamaged tendon can lead to further damage or injury. Prior damage mayresult in degeneration that requires a second more drastic procedure torepair the tendon. Further, if the prior procedure was only partiallysuccessful in relieving pain and discomfort, a response may be to usethe shoulder less which leads to degeneration and increased likelihoodof further injury along with the need for more drastic surgery. Further,it would be beneficial to be able to treat partial thickness tearsgreater than 50% without cutting the untorn portion of the tendon tocomplete the tear before suturing back together. There is a large needfor surgical techniques and systems to treat partial thickness tears andprevent future tendon damage by strengthening or repairing the nativetendon having the partial thickness tear.

SUMMARY OF THE DISCLOSURE

The present disclosure is generally directed to a fastener or staplethat can be used to attach an implant to bone or other tissue. Thestaple or fastener can be included in a kit or system that also caninclude a staple delivery device and a pilot hole forming trocarassembly. The trocar assembly is used to create pilot holes and retaininstrument position within those pilot holes for staple insertion. Thestaple delivery device can carry the staple into the pilot holes andrelease the staple in engagement with bone to retain the implant inposition.

The staple for insertion and retention in bone can include a bridgeportion having arms extending from proximate each end thereof, at leasta portion of each arm including tissue retention members, each tissueretention member having at least two barbed projections extendinglaterally therefrom. Each arm can have a cross sectional area of reducedstrength proximate each projection relative to other portions of thetissue retention member such that a portion of the tissue retentionmember flexes laterally proximate each projection in response to apullout force applied to the bridge. The tissue retention members caninclude a trunk of greater cross sectional area than a non-trunk portionof the arms.

The fastener or staple can also include, in alternative embodiments, afirst arm having a proximal end and a distal end, a second arm having aproximal end and a distal end, and a bridge connecting the first arm andsecond arm, wherein each of the first and second arms include a trunkportion extending over at least a portion of the length thereof. Eachtrunk can have a lateral extent larger than a lateral extent of thebridge or non-trunk arm portion adjacent thereto such that the stapleincludes a first change in lateral stiffness disposed proximate thebridge or non-trunk arm portion abutment with the first trunk and asecond change in lateral stiffness disposed proximate the bridge ornon-trunk arm portion abutment with the second trunk. The lateral extentof each trunk in at least one direction can be at least about threetimes the lateral extent of at least a portion of the bridge ornon-trunk portion of the arm.

Each trunk can further include a first projection and a secondprojection, the first projection including a first proximal surfaceextending away from the trunk in a first direction, the first directionbeing such that the first proximal surface will engage the tissue orbone when the trunk is inserted therein so that a first moment isapplied to the trunk in response to a pullout force on the bridge.Likewise, the second projection can include a second proximal surfaceextending away from the trunk in a second direction, the seconddirection being such that the second proximal surface will engage thetissue or bone when the trunk is inserted therein so that a secondmoment is applied to the trunk in response to a pullout force on thebridge. Each of the trunks can further include a localized area ofweakness proximate the second projection thereon. For example, a secondarea of reduced strength can include a slit in the cross section of thetissue retention member or trunk adjacent at least one of theprojections therefrom. Further, reduced strength can be created wherethe trunk meets the non-trunk portion of the arm adjacent thereto or thebridge.

In some embodiments, the change in lateral stiffness and the localizedarea of weakness allow flexing of each arm portion in response to thefirst and second moment, respectively.

The projections can be arranged to extend in first and second directionsto achieve increased pullout strength. The first direction can extendproximally and laterally away from each trunk while the second directioncan extend proximally and laterally away from each trunk and a lateralcomponent of the second direction is generally opposite a lateralcomponent of the first direction. The forces on the projections createmoments about the more flexible portions of the staple where thedirection of the first moment is generally opposite the direction of thesecond moment on each arm.

In some embodiments, the fastener first trunk and the second trunk eachdefine a cavity, each cavity being spaced laterally from the respectivenon-trunk portion or bridge adjacent thereto. Each cavity defined by thefirst and the second trunk is sized to receive a first stake and asecond stake, respectively, of a fastener delivery device. Each cavitydefined by the first and the second trunk can extend from the proximalend to the distal end of the trunk.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an exemplary tissue fasteneror staple in accordance with the present disclosure;

FIG. 2 is a an alternative perspective view of the tissue fastener orstaple of FIG. 1 illustrating other features in accordance with thepresent disclosure;

FIG. 3 is a top plan view of the tissue fastener or staple of FIG. 1illustrating the laterally extending legs having lumens for receivingthe stakes of a delivery device for positioning the staple in desiredtissue;

FIG. 4 is a front plan view of the tissue fastener or staple of FIG. 1illustrating in phantom flexing of the barbs and legs of the staple inresponse to grasping of tissue in one embodiment of the disclosure;

FIG. 5 is a stylized anterior view of a shoulder including a humerus anda scapula;

FIG. 6 is a stylized of a shoulder depicting the head of the humerusshown mating with the glenoid fossa of the scapula at a glenohumeraljoint and a sheet-like material is affixed to the tendon;

FIG. 7 is a stylized perspective view showing a portion of the body of ahuman patient divided into quadrants by planes for descriptive purposesherein;

FIG. 8 is a stylized perspective view illustrating an exemplaryprocedure for arthroscopic treatment of a shoulder of a patient inaccordance with one embodiment of the disclosure;

FIG. 9 is a stylized perspective view of a shoulder including asupraspinatus having a distal tendon with a sheet-like material affixedthereto;

FIG. 10A is a simplified perspective view of a tissue fastener or stapledelivery device in accordance with the present disclosure;

FIG. 10B is a simplified perspective view of a trocar assembly,including a trocar disposed within a guide sheath assembly for creatingpilot holes and retaining the sheath within the formed pilot holes fordelivery of a tissue fastener or staple by a device such as thatdepicted in FIG. 10A.

FIG. 11A is a perspective view of the sheath assembly of FIG. 10B withthe trocar removed;

FIG. 11B is a perspective view of the trocar of FIG. 10B as removed fromthe sheath assembly;

FIG. 11C is a perspective view of one pilot hole position retentionmember which is positioned in a distal portion of the sheath assembly inone embodiment of the present disclosure;

FIG. 12 is a perspective view depicting the sheath and staple pusherassemblies of a staple delivery device in one embodiment of thedisclosure;

FIG. 13 is a simplified exploded view of the tissue fastener or stapledelivery device of FIG. 10A depicting additional features thereof;

FIG. 14 depicts further features of the staple pusher assembly of FIG.13;

FIGS. 15A and 15B illustrate the features of the distal portion of thestaple pusher assembly of FIG. 13 with a staple mounted thereon inaccordance with one embodiment of the disclosure;

FIGS. 16A and 16B further illustrate the staple pusher assembly in oneembodiment of the disclosure;

FIG. 17 is a more detailed perspective view of the distal portion of thestaple pusher assembly illustrating stakes that mate with the staple inone embodiment of the disclosure;

FIG. 18A is simplified perspective view of a shoulder having an implantaffixed to the tendon and depicting the first step in a method ofdelivering fasteners to affix the implant to bone of the humeral head inaccordance with one method of the disclosure;

FIG. 18B is a simplified plan view of the distal portion of the trocarassembly as position to create pilot holes for affixing the implant tobone in a further step of a method of the disclosure;

FIG. 18C depicts the trocar assembly of FIG. 18B as inserted into thebone to form pilot holes in accordance with a method of the disclosure;

FIG. 18D depicts the trocar assembly with the trocar portion removed andthe remaining sheath assembly retaining its position in the pilot holesformed;

FIG. 18E is a partial perspective view of the articular side of thesupraspinatus tendon illustrating the position relative to the bicepstendon and a marker inserted from the bursal side to identify thelocation of the biceps tendon which is not visible from the bursal side;

FIG. 18F illustrates a fastener or staple as inserted in accordance witha method of the disclosure.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

FIG. 1 is a perspective view illustrating an exemplary staple 100 inaccordance with the present detailed description. With reference to FIG.1, it will be appreciated that staple 100 may assume variousorientations without deviating from the spirit and scope of thisdetailed description. Although the various parts of this exemplaryembodiment are depicted in relative proportion to other parts of thestaple 100, other configurations in size and orientation of the variousparts are possible. A number of reference directions are illustratedusing arrows in FIG. 1 to assist in understanding the details of thestaple 100. The illustrated directions include: a proximal direction P,a distal direction D, a first laterally outward direction LOA, a secondlaterally outward direction LOB, a first laterally inward direction LIA,and a second laterally inward direction LIB.

Staple 100 comprises a first arm 102A, a second arm 102B, and a bridge104 extending from, abutting or adjacent to the proximal end of firstarm 102A to the proximal end of second arm 102B. The first arm 102Aincludes a first trunk 106A extending for at a least a portion of thelength of the first arm 102A. As depicted in FIG. 1, a proximal portionof the first arm 102A abuts the proximal end of the first trunk 106A.The first arm 102A, in this embodiment includes the trunk portion 106Aand a non-trunk portion 105A. The length of first trunk 106A relative tothe overall length of the first arm 102A can vary in differentembodiments. The first trunk 106A can extend for the entire length ofthe first arm 102A such that the bridge abuts with or is adjacent to thetrunk 106A. Similarly, the second arm 102B includes a second trunk 106Bextending for at least a portion of the length of the second arm 102B. Aproximal portion of the second aim 102B abuts the proximal end of thesecond trunk 106B. The second arm 102B, in this embodiment includes thetrunk portion 106B and a non-trunk portion 105B. The length of secondtrunk 106B relative to the overall length of the second arm 102B canvary in different embodiments. The second trunk 106B can extend for theentire length of the second arm 102B such that the bridge abuts with oris adjacent to the trunk 106B. In FIG. 1, first trunk 106A and secondtrunk 106B are shown extending distally from a proximal portion of firstarm 102A and second arm 102B, respectively.

In the embodiment of FIG. 1, first trunk 106A has a lateral extent, orcross sectional area, that is larger than a lateral extent of thenon-trunk portion 105A of first arm 102A and bridge 104. The staple 100includes a first change in lateral stiffness 108A disposed where thedistal end of non-trunk portion 105A of first arm 102A abuts first trunk106A. As depicted, the change in stiffness is abrupt, but can be gradualin alternative embodiments. In an embodiment where the first trunk 106Aextends for the full length of the first arm 102A, the change instiffness occurs where the first trunk 106A abuts the bridge 104. Withreference to FIG. 1, it will be appreciated that first trunk 106A ismounted eccentrically to first arm 102A and second trunk 106B is mountedeccentrically to second arm 102B. As with first trunk 106A, second trunk106B has a lateral extent, or cross sectional area that is larger than alateral extent of second arm 102B or bridge 104. The staple 100 includesa second change in lateral stiffness 108B where the distal end of secondarm 102B abuts second trunk 106A in the embodiment of FIG. 1. If thesecond trunk 106B extends for the entire length of second arm 102B, thechange in stiffness occurs at the abutment with the bridge 104.

Each of the first trunk 106A and second trunk 106B can include at leasta first projection 122A, 122C and a second projection 122B, 122D, thefirst projection 122A, 122C on each trunk 106A, 106B includes a firstproximal surface 124A, 124C extending away from the trunk in a firstdirection, the first direction being such that the first proximalsurface 124A, 124C will engage the tissue or bone after the trunk isinserted therein and a pullout force is applied to the bridge 104. Thisforce creates a first moment centered on the area of reduced lateralextent adjacent the trunk, tending to rotate the trunk thereabout,further providing a greater holding force in response to the pulloutforce as the trunk presses against the tissue or bone. The secondprojection 122B, 122D includes a second proximal surface 124B, 124Dextending away from the trunk in a second direction, different from thefirst direction, the second direction being such that the secondproximal surfaces 124B, 124D will engage the tissue or bone after thetrunk is inserted therein and a pullout force is applied to the bridge104. A slit or area of reduced cross section in the trunk adjacent thesecond projections provide an area of weakness so that a second momentis applied to the trunk in response to a pullout force on the bridge104. This moment causes rotation of the trunk about the area of weaknessand increases the holding force with increased pullout force.

As specifically illustrated in the embodiment of staple or fastener 100in FIG. 1, first trunk 106A includes a first projection 122A disposed atan outer side of trunk 106A and a second projection 122B disposed at aninner side of the trunk. First projection 122A includes a first proximalsurface 124A extending away from first trunk 106A in a first direction.With reference to FIG. 1, it will be appreciated that the firstdirection has an outward lateral component and a proximal component sothat first proximal surface 124A extends outwardly and proximally awayfrom first trunk 106A. The first direction is selected such that firstproximal surface 124A will engage tissue or bone proximate the outerside of first trunk 106A after being inserted therein so that a firstmoment is applied to the trunk in response to a pullout force on bridge104. The moment centers on the arm portion of lesser cross sectionadjacent the first projection.

In the embodiment of FIG. 1, first trunk 106A includes a first localizedarea of weakness 120A disposed proximate second projection 122B. Secondprojection 122B includes a second proximal surface 124B extending awayfrom first trunk 106A in a second direction. The second direction isselected such that second proximal surface 124A will engage tissue orbone proximate the inner side of first trunk 106A when inserted thereinso that a second moment is applied to the trunk in response to a pulloutforce on bridge 104. The moment centers around the area of weakness120A. The second moment has a direction that is generally opposite adirection of the first moment. It will be appreciated that the seconddirection has an inward lateral component and a proximal component sothat second proximal surface 124B extends inwardly and proximally awayfrom first trunk 106A.

Second trunk 106B includes a third projection 122C disposed at an outerside of second trunk 106B and a fourth projection 122D disposed at aninner side of the trunk. In the embodiment of FIG. 1, third projection122C includes a third proximal surface 124C extending away from secondtrunk 106B in a third direction. With reference to FIG. 1, it will beappreciated that the third direction has an outward lateral componentand a proximal component so that third proximal surface 124C extendsoutwardly and proximally away from second trunk 106B. The thirddirection is selected such that third proximal surface 124C will engagetissue or bone proximate the outer side of second trunk 106B wheninserted therein so that a third moment is applied to the trunk inresponse to a pullout force on bridge 104.

In the embodiment of FIG. 1, second trunk 106B includes a secondlocalized area of weakness 120B disposed proximate fourth projection122D. Fourth projection 122D includes a fourth proximal surface 124Dextending away from second trunk 106B in a fourth direction. In theembodiment of FIG. 1, the fourth direction is selected such that secondproximal surface 124A will engage tissue or bone proximate the innerside of second trunk 106B when inserted therein so that a fourth momentis applied to the trunk in response to a pullout force on bridge 104.The fourth moment has a direction that is generally opposite a directionof the third moment. It will be appreciated that the fourth directionhas an inward lateral component and a proximal component so that fourthproximal surface 124D extends inwardly and proximally away from secondtrunk 106.

As depicted in FIG. 1, the staple 100 includes proximal projections thatextend away from or outward from the bridge 104, while the distalprojections extend inward or toward the center of the bridge 104. Thiscreates generally opposing forces in response to tension on the bridgewhich, in combination with areas of weakness or reduced lateral extent,substantially increases the holding force of the staple in bone as thedifferent portions of the trunks tend to rotate in opposite directionsand apply force to an opposing wall in the hole in bone in which thestaple is positioned. It is however, understood that otherconfigurations of the projections are possible. In some embodiments, atleast two projections are included and they extend in differentdirections to cause different force responses as tension is applied tothe bridge. It is believed this provides adequate holding force in bone,which can include differing thicknesses of hard and soft tissue alongwith porous areas.

In some useful embodiments, each projection of staple 100 may be cleftedto form a plurality of points for greater retention in tissue. In theexemplary embodiment of FIG. 1, first projection 122A of first trunk106A defines a first notch 126A that divides first projection 122A intoa first sub-projection and a second sub-projection. Second projection122B of second trunk 106B defines a second notch 126B. In the exemplaryembodiment of FIG. 1, second notch 126B divides second projection 122Binto a first sub-projection and a second sub-projection. Thirdprojection 122C of second trunk 106B defines a third notch 126C thatdivides third projection 122C into a first sub-projection and a secondsub-projection. Fourth projection 122D of second trunk 106B defines afourth notch 126D that divides fourth projection 122D into a firstsub-projection and a second sub-projection.

With continued reference to FIG. 1 and further reference to FIGS. 2 and3, first trunk 106A defines a first cavity 128A and second trunk 106Bdefines a second cavity 128B. In the exemplary embodiment of FIGS. 1, 2and 3, first cavity 128A extends into first trunk 106A and second cavity128B extends into second trunk 106B. The cavity is sized to cooperatewith a staple delivery device for holding and inserting the staple intotissue or bone, as later described in detail herein. In summary, thestaple delivery device includes longitudinally extending stakes that fitwithin the cavities 128A, 128B to hold the staple 100 and push it intoposition in the tissue as the stake abuts a portion of its respectivetrunk. In some embodiments the cavity may extend through a portion ofthe length of each trunk, as best depicted in FIG. 2 which indicates thedistal end of the staple 100 is closed. Alternatively, first cavity 128Aand second cavity 128B may extend through the entire length of eachtrunk 106A, 106B or other portions of staple 100 in some embodiments. Asillustrated by the top view of the staple 100 in FIG. 3, first cavity128A and second cavity 128B each have a generally rectangular or squarecross-sectional shape to cooperate with a similarly shaped cross sectionon a staple delivery device. However, that first cavity 128A and secondcavity 128B may have various cross-sectional shapes to cooperate withalternative staple delivery device designs without deviating from thespirit and scope of the present detailed description.

FIG. 4 is an alternative perspective view of the embodiment in FIG. 1illustrating an exemplary staple 100 in accordance with the presentdetailed description. In particular, FIG. 4 illustrates in phantom theflexing and bending of the trunks 106A and 106B after implant inresponse to tension applied to the bridge, as by tissue or an implantaffixed at an implant site. Staple 100 comprises a first arm 102A, asecond arm 102B, and a bridge 104 extending from the proximal end offirst arm 102A to the proximal end of second arm 102B. The distal end offirst arm non-trunk portion 105A abuts the proximal end of first trunk106A. Similarly, the distal end of second aim non-trunk portion 105Babuts the proximal end of a second trunk 106B. In FIG. 4, first trunk106A and second trunk 106B are shown extending distally from first arm102A and second arm 102B, respectively.

In the embodiment of FIG. 4, first trunk 106A has a lateral extent thatis larger than the lateral extent of the non-trunk portion 105A of firstarm 102A. This combination creates a relatively abrupt change in lateralstiffness 108A disposed where the distal end of the non-trunk portion108A of first arm 102A abuts first trunk 106A. With reference to FIG. 4,first trunk 106A is mounted eccentrically to first arm 102A and secondtrunk 106B is mounted eccentrically to second arm 102B, however, othermountings or abutments can be used, such as a non-trunk portion havingwalls that surround the cavity and include a lumen therethrough toaccess the cavity with a staple delivery stake. A change in lateralstiffness would still be accomplished where the lateral extend changed.Further, a change in lateral stiffness could be accomplished by using adifferent material for the non-trunk portion relative to the trunkportion. Second trunk 106B in combination with the non-trunk portion105B of second arm 102B provides the same change in lateral stiffness108B. The first arm 102A, the second arm 102B, and the bridge 104 may beintegrally formed of a polymeric material, such as polyether etherketone (PEEK).

As earlier described the configuration of the four projections 122A,122B, 122C and 122D, contact the tissue or bone and provide a holdingforce upon implantation. Each projection is positioned to provide aforce moment in a desired direction to the trunk in response to thepullout force on the bridge 104.

In the embodiment of FIG. 4, first trunk 106A and second trunk 106Binclude first and second localized areas of weakness 120A, 120B disposedproximate second projections 122B, 122D. This area of weakness is formedby a slit formed proximal of the projection. However, the area ofweakness could be formed by other means, such as a change in material,pinching or perforations.

The combination of projections, areas of weakness and changes in lateralextent provide desired flexing, bending and rotating of the trunk inresponse to pull out forces once implanted in a bone, such as in a pilothole formed in the bone. Together these components act as tissueretention members. An exemplary deflected shape is shown with dashedlines in FIG. 4. Staple 100 may be urged to assume the deflected shapeshown in FIG. 4, for example, by applying a pullout force on the bridge104 of the staple 100. Alternatively, distally directed forces can beapplied on staple 100 using, for example, the staple delivery systemshown later and described herein. In some applications, the stapledelivery tool may be used to urge first projection 122A and thirdprojection 122C into orientations which lock staple 100 into a targettissue. For example, first projection 122A and third projection 122C maybe rotated so that these projections engage the target tissue. When thisis the case, tension extending through bridge 104 of staple 100 may keepfirst projection 122A and third projection 122C in the rotated position.Also when this is the case, the projections may inhibit staple pullout.Further, rotation of any projection causes a rotational force and withinlimits defined by the hole in the bone some rotation to an adjacentportion of the trunk which contacts or engages the wall of the hole inthe bone. Increased pullout force results in increasing holding forcewith this design.

Next referring to FIG. 5, an exemplary use or application of the staplesof the present disclosure is described. FIG. 5 is a stylized anteriorview of a patient 20. For purposes of illustration, a shoulder 22 ofpatient 20 is shown in cross-section in FIG. 5. Shoulder 22 includes ahumerus 14 and a scapula 12. In FIG. 5, a head 24 of humerus 14 can beseen mating with a glenoid fossa of scapula 12 at a glenohumeral joint.With reference to FIG. 5, it will be appreciated that the glenoid fossacomprises a shallow depression in scapula 12. The movement of humerus 14relative to scapula 12 is controlled by a number of muscles including:the deltoid, the supraspinatus, the infraspinatus, the subscapularis,and the teres minor. For purposes of illustration, only thesupraspinatus 26 is shown in FIG. 5.

With reference to FIG. 5, a distal tendon 28 of the supraspinatus 26meets humerus 14 at an insertion point. Scapula 12 of shoulder 22includes an acromium 32. In FIG. 5, a subacromial bursa 34 is shownextending between acromium 32 of scapula 12 and head 24 of humerus 14.Subacromial bursa 34 is shown overlaying supraspinatus 26 as well assupraspinatus tendon 28 and a portion of humerus 14. Subacromial bursa34 is one of the hundreds of bursae found the human body. Each bursacomprises a fluid filled sac. The presence of these bursae in the bodyreduces friction between bodily tissues.

The exemplary staples or fasteners described herein may be used to affixtendon repair implants to various target tissues. The shoulder depictedin FIG. 5 is one example where a tendon repair implant may be affixed toone or more bones associated with an articulating joint, such as theglenohumeral joint. Additionally, the tendon repair implant may beaffixed to one or more tendons to be treated. The tendons to be treatedmay be torn, partially torn, have internal micro-tears, be untorn,and/or be thinned due to age, injury or overuse. Applicants believe thatthe methods and apparatus of the present application and related devicesmay provide very beneficial therapeutic effect on a patient experiencingjoint pain believed to be caused by partial thickness tears and/orinternal microtears. By applying a tendon-repair implant early before afull tear or other injury develops, the implant may cause the tendon tothicken and/or at least partially repair itself, thereby avoiding moreextensive joint damage, pain, and the need for more extensive jointrepair surgery.

FIG. 6 is a stylized anterior view of a shoulder 22 including a humerus14 and a scapula 12. In FIG. 6, a head 24 of humerus 14 is shown matingwith a glenoid fossa of scapula 12 at a glenohumeral joint. Asupraspinatus 26 is also shown in FIG. 6. This muscle, along withothers, controls the movement of humerus 14 relative to scapula 12. Adistal tendon 28 of supraspinatus 26 meets humerus 14 at an insertionpoint 30.

As depicted in FIG. 6, distal tendon 28 includes a first damaged portion36. A number of loose tendon fibers 40 in first damaged portion 36 arevisible in FIG. 6. First damaged portion 36 includes a first tear 42extending partially through distal tendon 28. First tear 42 maytherefore be referred to as a partial thickness tear. With reference toFIG. 6, first tear 42 begins on the side of distal tendon 28 facing thesubacromial bursa (shown in the previous Figure) and ends midway throughdistal tendon 28. Accordingly, first tear 42 may be referred to as abursal side tear.

With reference to FIG. 6, distal tendon 28 includes a second damagedportion 38 located near insertion point 30. As illustrated, seconddamaged portion 38 of distal tendon 28 has become frayed and a number ofloose tendon fibers 40 are visible. Second damaged portion 38 of distaltendon 28 includes second tear 44. Second tear 44 begins on the side ofdistal tendon 28 facing the center of the humeral head 24. Accordingly,second damaged portion 38 may be referred to as an articular side tear.

FIG. 6 illustrates a sheet-like implant 50 has been placed over thebursal side of distal tendon 28. The sheet-like implant 50 is affixed todistal tendon 28 by a plurality of tendon staples 51. Sheet-like implant50 is affixed to humerus 14 by a plurality of bone staples 100 inaccordance with designs of staples disclosed herein. Sheet-like implant50 extends over insertion point 30, first tear 42 and second tear 44.Some useful methods in accordance with this detailed description mayinclude placing a tendon repair implant on the bursal side of a tendonregardless of whether the tears being treated are on the bursal side,articular side or within the tendon. In some cases the exact locationand nature of the tears being treated may be unknown. A tendon repairimplant may be applied to the bursal side of a tendon to treat shoulderpain that is most likely caused by one or more partial thickness tearsin the tendon.

FIG. 7 is a stylized perspective view showing a portion of the body 82of a human patient 20. Body 82 includes a shoulder 22. In the exemplaryembodiment of FIG. 7, a plurality of cannulas are positioned to access atreatment site within shoulder 22. In some cases, shoulder 22 may beinflated by pumping a continuous flow of saline through shoulder 22 tocreate a cavity proximate the treatment site. The cannulas shown in FIG.7 include a first cannula 80A, a second cannula 80B and a third cannula80C.

In FIG. 7, a sagital plane SP and a frontal plane FP are shownintersecting body 82. Sagital plane SP and frontal plane FP intersectone another at a medial axis MA of body 82. With reference to FIG. 7,sagital plane SP bisects body 82 into a right side 84 and a left side86. Also with reference to FIG. 7, frontal plane FP divides body 82 intoan anterior portion 92 and a posterior portion 88. Sagital plane SP anda frontal plane FP are generally perpendicular to one another. Theseplanes and portions are used to describe the procedures used inexemplary embodiments.

First cannula 80A is accessing a treatment site within shoulder 22 usinga lateral approach in which first cannula 80A pierces the outer surfaceof right side 84 of body 82. The term lateral approach could also beused to describe situations in which an instrument pierces the outersurface of left side 86 of body 82. Second cannula 80B is accessing atreatment site within shoulder 22 using a posterior approach in whichsecond cannula 80B pierces the outer surface of posterior portion 88 ofbody 82. Third cannula 80C is accessing a treatment site within shoulder22 using an anterior approach in which third cannula 80C pierces theouter surface of anterior portion 92 of body 82.

FIG. 8 is a stylized perspective view illustrating an exemplaryprocedure for treating a shoulder 22 of a patient 20. The procedureillustrated in FIG. 8 may include, for example, fixing tendon repairimplants to one or more tendons of shoulder 22. The tendons treated maybe torn, partially torn, have internal micro-tears, be untorn, and/or bethinned due to age, injury or overuse.

Shoulder 22 of FIG. 8 has been inflated to create a cavity therein. Afluid supply 52 is pumping a continuous flow of saline into the cavity.This flow of saline exits the cavity via a fluid drain 54. A camera 56provides images from inside the cavity. The images provided by camera 56may be viewed on a display 58.

Camera 56 may be used to visually inspect the tendons of shoulder 22 fordamage. A tendon repair implant in accordance with this disclosure maybe affixed to a bursal surface of the tendon regardless of whether thereare visible signs of tendon damage. Applicants believe that the methodsand apparatus of the present application and related devices may providevery beneficial therapeutic effect on a patient experiencing joint painbelieved to be caused by internal microtears, but having no clear signsof tendon tears. By applying a tendon repair implant early before a fulltear or other injury develops, the implant may cause the tendon tothicken and/or at least partially repair itself, thereby avoiding moreextensive joint damage, pain, and the need for more extensive jointrepair surgery.

An implant delivery system 60 can be seen extending from shoulder 22 inFIG. 8. Implant delivery system 60 is extending through a first cannula80A. In certain embodiments, first cannula 80A can access a treatmentsite within shoulder 22 using a lateral approach in which first cannula80A pierces the outer surface of a right side of the patient's body. Insome cases a physician may choose not to use a cannula in conjunctionwith implant delivery system 60. When that is the case, the implantdelivery system may be advanced through tissue. Implant delivery system60 comprises a sheath that is affixed to a handle. The sheath defines alumen and a distal opening fluidly communicating with the lumen. In theembodiment of FIG. 8, the distal opening of the sheath has been placedin fluid communication with the cavity created in shoulder 22.

A tendon repair implant is at least partially disposed in the lumendefined by the sheath of implant delivery system 60. Implant deliverysystem 60 can be used to place the tendon repair implant inside shoulder22. In some embodiments, the tendon repair implant is folded into acompact configuration when inside the lumen of the sheath. When this isthe case, implant delivery system 60 may be used to unfold the tendonrepair implant into an expanded shape. Additionally, implant deliverysystem 60 can be used to hold the tendon repair implant against thetendon.

The tendon repair implant may be affixed to the tendon while it is heldagainst the tendon by implant delivery system 60. Various attachmentelements may be used to fix the tendon-repair implant to the tendon.Examples of attachment elements that may be suitable in someapplications include sutures, tissue anchors, bone anchors, and staples.In the exemplary embodiment of FIG. 8, the shaft of a fixation tool 70is shown extending into shoulder 22. In one exemplary embodiment,fixation tool 70 is capable of fixing the tendon repair implant to thetendon and bone with one or more staples of the present disclosure whilethe tendon repair implant may held against the tendon by implantdelivery system 60.

FIG. 9 is a stylized perspective view of a shoulder 22 including asupraspinatus 26 having a distal tendon 28. With reference to FIG. 9, atendon repair implant 50 has been affixed to a surface of distal tendon28. Tendon repair implant 50 may comprise, for example, varioussheet-like structures without deviating from the spirit and scope of thepresent detailed description. In some useful embodiments, the sheet-likestructure may comprise a plurality of fibers. The fibers may beinterlinked with one another. When this is the case, the sheet-likestructure may comprise a plurality of apertures comprising theinterstitial spaces between fibers. Various processes may be used tointerlink the fibers with one another. Examples of processes that may besuitable in some applications including weaving, knitting, and braiding.In some embodiments, the sheet-like structure may comprise a laminateincluding multiple layers of film with each layer of film defining aplurality of micro-machined or formed holes. The sheet-like structure ofthe tendon repair implant may also comprise a reconstituted collagenmaterial having a porous structure. Additionally, the sheet-likestructure of the tendon repair implant may also comprise a plurality ofelectro-spun nanofiber filaments forming a composite sheet.Additionally, the sheet-like structure may comprise a synthetic spongematerial that defines a plurality of pores. The sheet-like structure mayalso comprise a reticulated foam material. Reticulated foam materialsthat may be suitable in some applications are available from BiomerixCorporation of Fremont, Calif. which identifies these materials usingthe trademark BIOMATERIAL™. The sheet-like structure may be circular,oval, oblong, square, rectangular, or other shape configured to suit thetarget anatomy.

Various attachment elements may be used to fix tendon repair implant 50to distal tendon 28 without deviating from the spirit and scope of thisdetailed description. Examples of attachment elements that may besuitable in some applications include sutures, tissue anchors, boneanchors, and staples. In the embodiment of FIG. 9, sheet-like implant 50is affixed to distal tendon 28 by a plurality of tendon staples 51.Sheet-like implant 50 is affixed to humerus 14 by a plurality of bonestaples 100 as described with respect to the exemplary embodiment ofFIG. 1 and detailed throughout this disclosure.

In some exemplary methods, a plurality of staples may be applied using afixation tool. After the staples are applied, the fixation tool may bewithdrawn from the body of the patient. Distal tendon 28 meets humerus14 at an insertion point 30. With reference to FIG. 9, it will beappreciated that sheet-like implant 50 extends over insertion point 30.Tendon repair implant may be applied to distal tendon 28, for example,using the procedure illustrated in the previous figures. In variousembodiments, staples may straddle the perimeter edge of the sheet-likeimplant (as shown in FIG. 9), may be applied adjacent to the perimeter,and/or be applied to a central region of the implant. In someembodiments, the staples may be used to attach the implant to softtissue and/or to bone.

Staples or fasteners 100, as exemplified in FIG. 1 and described andillustrated herein can be used to attach tissue and implants to bone. Inat least some embodiments, the staple is generally flexible and includesareas of relative lateral weakness on the trunks and can further includean increase in flexibility at the transition from the trunk to thenon-trunk portion of the arm or the transition from the trunk to thebridge. As described above, these areas of increased flexibility provideimproved staple retention as these portions allow flexing and bending inresponse to increasing pullout forces. With this flexibility, thefasteners cannot be pounded or driven into bone or other tissue as aconventional hard staple would be driven into paper, wood, tissue orbone. Therefore, for application of the staple of the present disclosureto affixing tissue or implants to bone, the staple is generally includedin a kit that also includes a staple delivery device 200 and a pilothole forming trocar assembly 300, as schematically illustrated in FIGS.10A and 10B, respectively.

In general, the staple delivery device 200 can include a handle assembly201 and a barrel assembly 205. The handle assembly 201 includes atrigger 203 that is operatively coupled to mechanisms in the barrelassembly 205 to deploy a staple of the present disclosure in bone. Thestaple delivery device 200 can be used in conjunction with the pilothole forming trocar assembly 300 of FIG. 10B.

The pilot hole forming trocar assembly 300, illustrated generally inFIG. 10B includes a trocar 302 and a position retention sleeve 304. Thetrocar 302 is releasably coupled to the position retention sleeve 304and slides in keyed arrangement within the sleeve 304 when uncoupled.The trocar 302 includes a distal portion having a retractable blade 306and a pair of pilot hole forming spikes 308 extending distally from thetrocar shaft. The retractable blade 306 is useful in inserting theassembly through an incision. The retractable blade 306 can be retractedin this embodiment by activating release button 315 which causes aspring (not shown) to pull the retractable blade 306 into the shaft ofthe trocar within the position retention sleeve 304. In this theposition, the pilot hole forming spikes remain extended from the shaft.In some embodiments the retractable blade 306 can be omitted if thepilot hole forming trocar assembly is to be inserted into an incisionthat already has a cannula extending therethrough to provide aninstrument path.

Referring to FIGS. 11A-11C, details of the elements of one embodiment ofa pilot hole forming trocar assembly 300 are illustrated. The pilot holeforming trocar assembly is used to created pilot holes in a bone forsubsequent placement of a staple or fastener, such as staple 100 ofFIG. 1. Further, the pilot hole forming trocar assembly includes a meansfor retaining instrument position with respect to the pilot holes whenthe trocar is removed so that a staple delivery device 200 can beinserted and the staple be in alignment with the already formed pilotholes. This prevents the time and difficulty associated with finding thepilot holes with the staple, which in fact may not be possible for manypractitioners.

As previously stated, a pilot hole forming trocar assembly 300 caninclude a trocar 302 and a position retention sleeve 304. One embodimentof a position retention sleeve 304 is illustrated in FIG. 11A. Theposition retention sleeve 304 includes a shaft 311 having a lumen 310extending therethrough. The lumen 310 is sized to receive the trocar 302when used to form pilot holes. The lumen 310 is also sized to receive astaple delivery device 200 when used to position a staple in a pilothole formed in bone. The lumen is shaped or keyed to cooperate witheither of these instruments or other instruments so that relativerotational position of the trocar 302 or staple delivery device 200 isfixed when slidably positioned in the position retention sleeve. Anopening or window 313 may be included near the distal end of theposition retention sleeve to allow viewing of devices inserted therein.

Position retention members 314 extend distally from the shaft 311. Asdetailed in FIG. 11C, the position retention members can be included onan insert 312 that is affixed proximate the distal end of the shaft 311.Alternatively, the position retention members can be integral to theshaft 311. The position retention members are sized and designed toextend into pilot holes as they are foamed by the trocar 302 describedbelow. When the trocar 302 is removed, the position retention members314, along with the sleeve 311 remain in position to provide a guide forthe staple delivery device 200 to be inserted into proper position andposition a staple 100 in the pilot holes. As depicted, the positionretention members 314 can include longitudinally extendingsemi-cylindrical projections. In the disclosed embodiment, the pilothole forming spikes 308 of the trocar 302 slide within the partiallumens of the position retention members 314. This design can providesupport for the spikes as they are pounded into bone and can also allowthe position retention members to readily slide into pilot holes formedby the spikes 308.

A more detailed depiction of one alternative embodiment of a trocar 302is included in FIG. 11B. The trocar includes a shaft 320 having at itsproximal end a knob 324 that can be used to pound or push the trocar 302into bone. The trocar can further include a collar 322 which can be usedto releasable engage the position retention sleeve 304 when the two aremated for forming pilot holes. A spring 323 can be included which causesor aids the retraction of the trocar when it is released from theposition retention sleeve.

As previously disclosed, the distal end of the trocar 302 includes twopilot hole forming spikes 308 extending from shaft 320. A retractableblade 306 is positioned between the spikes 308. In use, the blade 306 isretracted prior to the spikes 308 being used to form pilot holes inbone.

Now referring to FIG. 12, the two main components of one embodiment ofthe barrel assembly 205 are illustrated. The barrel assembly includes anouter sleeve 250 having a lumen 251 extending therethrough. The outersleeve 250 is secured to the handle assembly 201 in fixed relationshipwhen the staple delivery device 200 is assembled. A staple deliveryassembly 252 is slidably disposed in the lumen 251 and includes aproximal end 254 extending beyond the proximal end of the sleeve 250.The proximal end 254 of the staple delivery assembly 252 operativelyinteracts with trigger assembly 203 when the barrel 205 is mounted onthe handle assembly 201. In the embodiment of FIG. 12, the outer surfaceof the sleeve 250 is shaped so as to be rotationally keyed and sized fordesired fitting within the position retention sleeve 304. The sleeve 250includes a flat surface 257 keyed to fit within a flat surface on theinterior of the position retention sleeve 304.

The operation of some embodiments of the staple delivery device 200 isfurther understood with reference to FIG. 13. FIG. 13 is an explodedview showing the staple delivery device 200 that may be used inconjunction with a staple 100 and the above described pilot hole formingtrocar 300. The handle assembly 201 and barrel assembly 205 are shownwith the barrel assembly including both the sleeve 250 and stapledelivery assembly 252 included. Staple delivery assembly 252 includes afork 232, a shaft 240, and two staple setting rods 234. Staple settingrods 234 include a first staple setting rod 234A and a second staplesetting rod 234B. Both staple setting rods 234 are affixed to a rodcoupler 236 of staple delivery assembly 252 in the embodiment of FIG.13. When the barrel 205 is in an assembled state, first staple settingrod 234A and second staple setting rod 234B can extend through twogrooves defined by shaft 240. Each groove is dimensioned so that astaple setting rod can be partially disposed therein while the sleeve250 surrounds the staple setting rods 234 and shaft 240.

When staple delivery device 200 is in an assembled state, staple 100 maybe carried by a first stake 238A and a second stake 238B of fork 232. Aspreviously described with respect to FIG. 1, staple 100 can include afirst aim 102A, a second arm 102B, and a bridge 104 extending from theproximal end of first arm 102A to the proximal end of second arm 102B.The distal end of the non-trunk portion of first arm 102A abuts theproximal end of a first trunk 106A. Similarly, the distal end of thenon-trunk portion of second arm 102B abuts the proximal end of a secondtrunk 106B.

Now referring to FIGS. 14-17, details of some exemplary embodiments andfeatures of the staple delivery assembly 252 and the mounting anddelivery of a staple 100 are illustrated. Various aspects of theseelements may be included in embodiments of the overall staple deliverydevice 200 of this disclosure.

The components of a staple delivery assembly 252 are illustrated in FIG.14. First stake 238A and second stake 238B of fork 232 can be seenextending distally away from a distal end of shaft 240 in FIG. 14. Thedistal direction is indicated with an arrow D. In the embodiment of FIG.14, first stake 238A includes a distal portion 244A and a proximalportion 246A. Second stake 238B includes a distal portion 244B and aproximal portion 246B. In some useful embodiments, each distal portion244 is dimensioned to extend into a cavity defined by a staple, such ascavity 128A, 128B of staple 100 in FIG. 1. When this is the case, thestaple may be supported by each distal portion 244 that extends into apassage defined by the staple. In this way, fork 232 may be used tocarry a staple. Staple 100 is illustrated proximate the distal end ofshaft 240 to show the staple features relative to the staple deliveryassembly 252 prior to mounting the staple thereon. Staple setting rods234 are illustrated as attached to rod coupler 236 and it can be seenhow these rods can slidably engage the channels running longitudinallyon shaft 240. Spring 242 is also depicted.

In FIGS. 15A and 15B, the staple setting rods 234, fork 232 and staple100 are shown as initially assembled in one embodiment, prior to addingshaft 240. In particular, FIG. 15B depicts fork 232 slidably disposed inchannels 233. It further shows the way in which staple settings rods aredisposed within cavities in the staple and the distal ends of the staplesetting rods 234 extend to abut a proximal surface of the staple, inthis embodiment the proximal surface is the proximal end of the trunk.In some useful methods, staple setting rods 234 are moved distally toapply pushing forces to one or more proximal surfaces of staple 100.These pushing forces may be used, for example, to urge first projection122A and third projection 122C into orientations that lock staple 100into a target tissue. For example, first projection 122A and thirdprojection 122C may be rotated so that these projections engage thetarget tissue. When this is the case, tension extending through bridge104 of staple 100 may keep first projection 122A and third projection122C in the rotated position. Also when this is the case, theprojections may inhibit staple pullout.

In FIGS. 16A and 16B, the initial assembly of FIG. 15A is shown with theshaft 240 in position, along with the staple setting rods affixed to therod coupler 236 and the spring positioned between the rod coupler 236and the proximal end of the shaft 240. The spring 242 of staple deliveryassembly 252 may be compressed as staple setting rods 234 are moveddistally to urge first projection 122A and third projection 122C intoorientations that lock staple 100 into a target tissue. After staple 100has been set, spring 242 may urge staple setting rods 234 proximallytoward a starting position. When staple delivery assembly 252 is in anassembled state, a distal end of spring 242 is seated against a proximalend of shaft 240 and a proximal end of spring 242 is seated against thedistal end of rod coupler 236. Spring 242 may deflect as staple settingrods 234 are moved proximally and distally relative to shaft 140. Distaland proximal directions are indicated with arrows labeled D and P.

FIG. 17 is a perspective view further illustrating fork 232 shown moregenerally in the previous figures. Fork 232 includes a first stake 238Aand a second stake 238B. First stake 238A includes a distal portion 244Aand a proximal portion 246A. Second stake 238B includes a distal portion244B and a proximal portion 246B. The proximal portion 246 of each stake238 has generally dovetail-shaped lateral cross-section. In some usefulembodiments, each proximal portion 246 is dimensioned to be received ina dovetail-shaped slot defined by a staple setting rod 234. When this isthe case, the staple setting rod and the fork are coupled to each otherwith a single degree of freedom for relative movement such that thestaple setting rod can slide in distal and proximal directions relativeto the fork, as previously described.

As depicted in the prior drawings, the manner in which a staple 100, afirst staple setting rod 234A and a second staple setting rod 234Bengage fork 232 allows placement of the staple with active engagementand retention in the tissue or bone. Each staple setting rod 234 isdisposed in sliding engagement with fork 232. A distal end of eachstaple setting rod 234 is disposed near a staple 100 that is carried byfork 232.

Staple 100 is designed to cooperatively engage the fork and staplesetting rods when mounted thereon for placement in bone. As previouslydescribed, the staple 100 can include a first arm 102A, a second arm102B, and a bridge 104 extending from the proximal end of first arm 102Ato the proximal end of second arm 102B. At least the distal portion offirst arm 102A is a trunk that abuts a non-trunk portion of first arm102A or the bridge 104. The same is true of second arm 102B. First trunk106A and second trunk 106B define a first cavity 128A and a secondcavity 128B, respectively.

Fork 132 includes a first stake 238A and a second stake 238B. A distalportion 244A of first stake 238A of fork 232 can be seen extending intofirst cavity 128A defined by first trunk 106A of staple 100. A distalportion 244B of second stake 238B of fork 232 extends into second cavity128B defined by second trunk 106B of staple 100.

The proximal portion of each stake 238 has a generally dovetail-shapedlateral cross-section. Proximal portion 246A of first stake 238A isslidingly received in a dovetail-shaped slot defined by first staplesetting rod 234A. Similarly, proximal portion 246B of second stake 238Bis slidingly received in a dovetail-shaped slot defined by second staplesetting rod 234B. Accordingly, each staple setting rod is coupled tofork 232 with a single degree of freedom for relative movement such thatthe staple setting rod can slide in distal and proximal directionsrelative to the fork.

The staple setting rods 234 may be moved so that the distal end of eachstaple setting rod abuts a proximal surface of staple 100. Each staplesetting rod may apply pushing forces to one or more proximal surfaces ofstaple 100. Forces applied by the staple setting rods may be used tourge first projection 122A and third projection 122C into orientationsthat lock staple 100 into a target tissue. For example, first projection122A and third projection 122C may be rotated so that these projectionsengage the target tissue. When this is the case, tension extendingthrough bridge 104 of staple 100 may keep first projection 122A andthird projection 122C in the rotated position in which the projectionsinhibit staple pullout.

As assembled, the distal end of the staple delivery assembly 252 isenclosed by the end of the sheath 250. Initial movement of the triggercauses the stable delivery assembly to extend beyond the distal end ofthe sheath 150 which inserts the staple 100 into pilot holes in thebone. Continue movement of the trigger then forces the staple settingrods distally to set the staples in engagement with the bone.

The process of forming pilot holes and delivery staples of the presentdisclosure to bone is described with respect to FIGS. 18A-18F whichdepict the various steps in affixing an implant 50 to bone with staplesor fasteners of the present disclosure. FIG. 18A schematically depicts ashoulder 22 of a patient 20 having an implant 50 positioned over asupraspinitus tendon 28. The implant is partially affixed to the tendon28 with fasteners 51 and extends laterally to and over the insertionpoint of the tendon to the humeral head 24. As depicted, the implant 50is not yet affixed to the humeral head 24. A distal portion of a pilothole forming trocar assembly 300, in particular the position retentionsleeve 304, is disposed over a desired location near the lateral edge ofthe implant 50 where it overlies the humeral head 24. It is noted theFIG. 18A is a depiction with all overlying tissue removed from theshoulder 22 to clearly show the location of the entire implant 50 on thesupraspinitus tendon 28. This view is not possible during actualarthroscopic procedures in which the fasteners and instruments of thepresent disclosure can be used, however the depiction provides a clearunderstanding of the placement of an implant and the use of fastenersdisclosed herein. In actual use the surgeon will have a side view from aviewing scope (not shown) of a small space created by inflating the areawith fluid and clearing necessary obstructions from the implant area.

FIG. 18B is a schematic illustration of a cross-sectional side view ofthe partially affixed implant of FIG. 18A showing the small portion ofthe implant 50 that is not yet affixed to the humeral head 24. As can beseen in the illustration, the humeral head 24 is shown in cross-sectionwhich illustrates the composite nature of bone structure. In general,bone includes hard outer portion or cortical layer 375 and a poroussofter inner portion or cancellous bone 376. The pilot hole formingtrocar assembly 300 is positioned with the spikes 308 over a selectedposition on the implant 50. As previously discussed, the trocar 302 ispositioned within the lumen of the position retention sleeve 304 withspikes 308 extending distally. The spikes 308 can be used to manipulateand position the implant as needed. Once in position, the spikes 308 canbe driven into the bone.

Referring to FIG. 18C, the illustration of FIG. 18B is re-illustratedwith the pilot hole forming trocar 300 spikes pounded or otherwisedriven into the humeral head 24, penetrating the cortical layer 375 intothe cancellous portion 376. As illustrated, position retention members314 also penetrate the bone with the spikes 308. In FIG. 18D, it isillustrated that the trocar 302 and its distal spikes 308 are nowremoved leaving formed pilot holes 309 with the position retentionsleeve 304 remaining in position with position retention member 314extending into pilot holes 309. The position retention member 304 lumenprovides a guide to the pilot holes 309 for a staple delivery device200. In FIG. 18E, a staple 100 is shown extending into the pilot holes309 as mounted on the distal end of a staple delivery device 200 thathas been inserted into the lumen of position retention member 304. Inthis position the staple can be delivered and retained in the tissue orbone as previously described in the various embodiments disclosedherein. FIG. 18F depicts a staple 100 as delivered into bone with bridge304 holding the implant in position on the bone and arms of the stapleretaining position in the in the bone, such as within the cancellousportion 376.

While exemplary embodiments of the present invention have been shown anddescribed, modifications may be made, and it is therefore intended inthe appended claims and subsequently filed claims to cover all suchchanges and modifications which fall within the true spirit and scope ofthe invention.

What is claimed is:
 1. A method of securing an implant to tissue orbone, comprising: positioning the implant at a treatment site; driving apilot hole forming assembly through the implant and into the tissue orbone to form first and second pilot holes in the tissue or bone; andinserting a first arm of a fastener through the implant into the firstpilot hole and a second arm of the fastener through the implant into thesecond pilot hole; wherein the fastener further includes a bridgeconnecting a proximal end of the first arm and a proximal end of thesecond arm, wherein each of the first and second arms includes a trunkportion having only one first projection extending from the trunkportion at a first longitudinal location along the trunk portion and thetrunk portion having only one second projection extending from the trunkportion at a second longitudinal location along the trunk portion, thesecond location being spaced apart longitudinally from the firstlocation distal of the first location, the first projection extendingaway from the trunk portion in a first direction such that a firstmoment is applied to the trunk portion in response to a pullout force onthe bridge, the second projection extending away from the trunk portionin a second direction opposite the first direction such that a secondmoment is applied to the trunk portion in an opposite direction to thefirst direction in response to a pullout force on the bridge; whereinthe trunk portion of each of the first and second arms includes alocalized area of weakness at only the second location; wherein a firstportion of the trunk portion proximal of the area of weakness rotatesrelative to a second portion of the trunk portion distal of the area ofweakness in response to the second moment.
 2. The method of claim 1,further comprising: after forming the first and second pilot holes,maintaining a portion of the pilot hole forming assembly in the firstand second pilot holes; wherein the first and second arms of thefastener are inserted along the portion of the pilot hole formingassembly.
 3. The method of claim 1, wherein the bridge has a lateralextent less than a lateral extent of each trunk portion.
 4. The methodof claim 1, wherein each of the first and second arms comprises anon-trunk portion having a reduced lateral stiffness compared to thetrunk portion.
 5. The method of claim 4, wherein the non-trunk portionhas a lateral extent less than a lateral extent of the trunk portion. 6.The method of claim 4, wherein a distal end of the non-trunk portionabuts a proximal end of the trunk portion.
 7. The method of claim 6,wherein the change in lateral stiffness at the location where the distalend of the non-trunk portion abuts the proximal end of the trunk portionpermits flexing of each trunk portion in response to the first moment.8. The method of claim 1, wherein the localized area of weakness isformed by a slit formed proximal of the second projection.
 9. The methodof claim 1, further comprising: urging the first and second projectionsof each of the first and second arms into orientations which lock thefastener into the tissue or bone using the fastener delivery tool. 10.The method of claim 9, wherein urging the first and second projectionsof each of the first and second arms includes rotating the first andsecond projections within their respective pilot holes.
 11. A method ofsecuring an implant to tissue or bone, comprising: positioning theimplant at a treatment site; driving a pilot hole forming assemblythrough the implant and into the tissue or bone to form first and secondpilot holes in the tissue or bone; inserting a first arm of a fastenerthrough the implant into the first pilot hole and a second arm of thefastener through the implant into the second pilot hole; wherein thefastener further includes a bridge connecting the first arm and thesecond arm, wherein each of the first and second arms includes a trunkportion having only one first projection extending from the trunkportion at a first longitudinal location along the trunk portion and thetrunk portion having only one second projection extending from the trunkportion at a second longitudinal location along the trunk portion, thesecond location being spaced apart longitudinally from the firstlocation distal of the first location, the non-trunk portion having areduced lateral extent compared to the non-trunk portion, the firstprojection extending away from the trunk portion in a first directionsuch that a first moment is applied to the trunk portion in response toa pullout force on the bridge, the second projection extending away fromthe trunk portion in a second direction different from the firstdirection such that a second moment is applied to the trunk portion inresponse to the pullout force on the bridge; causing rotation of thetrunk portion relative to the non-trunk portion by the first moment; andcausing rotation of the trunk portion about an area of weaknessproximate only the second projection by the second moment.
 12. Themethod of claim 11, wherein different portions of the trunk portionrotate in opposite directions in response to the pullout force on thebridge.
 13. The method of claim 11, wherein the first direction extendsproximally and laterally away from each trunk portion, the seconddirection extends proximally and laterally away from the each trunkportion and a lateral component of the second direction is generallyopposite a lateral component of the first direction.
 14. The method ofclaim 11, wherein the area of weakness is formed by a slit formedproximal of the second projection.
 15. A method of securing an implantto tissue or bone, comprising: positioning the implant at a treatmentsite; driving a pilot hole forming assembly through the implant and intothe tissue or bone to form first and second pilot holes in the tissue orbone; inserting a first arm of a staple through the implant into thefirst pilot hole and a second arm of the staple through the implant intothe second pilot hole; wherein the staple further includes a bridgeconnecting the first arm and the second arm, wherein each of the firstand second arms includes a trunk portion having: only one firstprojection extending from the trunk portion at a proximal end of thetrunk portion; a single slot extending into the trunk portionintermediate the proximal end of the trunk portion and a distal end ofthe trunk portion; and only one second projection extending from thetrunk portion at the slot; wherein the first projection extends awayfrom the trunk portion in a first direction such that a first moment isapplied to the trunk portion in response to a pullout force on thebridge, and wherein the second projection extends away from the trunkportion in a second direction different from the first direction suchthat a second moment is applied to the trunk portion in response to thepullout force on the bridge; and causing a first portion of the trunkportion proximal of the slot to rotate relative to a second portion ofthe trunk portion distal of the slot in response to the pullout force.